>>> I found an old SAE paper 730119 on the OMC engine.
>>> A very interesting paper.
>>> I noticed that OMC had good luck with aluminum
>>> side housings made from hypereutectic aluminum.
>>> The same process used by GM on the Vega engine.
>>> Does anybody have any direct experience with
>>> OMC snow mobile rotary engine side housing wear problems?
>>> >>> I wonder how Silicon Nitride ceramic
>>> side seals would work on hypereutectic aluminum.
>>> >>> Perhaps OMC was better able to control the casting
>>> process than GM.
>>> >>> >>> Paul Lamar ...No rotor no motor.
>>> >>> Paul,
>>> I mentioned this before, and perhaps you heard differently through
your
>>> Chapparal contacts, but I was told the engine blocks on the Vega
engine
>>> worked fine by people in the know. Many other problems including valve
>>> guides which caused most of the smokers rather than the block.The
>>> Porsche 928 V8 and many of the current MB V8's use the same
technology.
>>> I thought this might be a good possibility, but I doubt that Mazda
would
>>> have missed it if that had been the case.
>>> Bill Jepson
>> >> >> BMW had problems with the sulfur content in US gasoline eating
up the
>> bore in their aluminum blocks on the 3L V8 (530i cars) - 10 years ago.
>> I haven't heard of more recent issues.
>> >> Other question.. It's my impression that the apex seals take more
>> abuse than the side seals, and similarly the rotor housing wear
>> surface needs to be tougher than the side housing wear surface. Is
>> this correct? Does that allow using a coating that's less tough on
>> the side housing? It's apples to oranges, right?
>> >> >> >> Regards,
>> >> Matt-
>> >> I would say yes Matt. Just an impression I get. However the side
housings
>> wear more than the rotor housings. Once the ridges are over a couple of
>> thou the housings need lapping or replacing. I suspect the cast iron
side
>> housings could benefit from the same chrome treatment given to the
>> rotor housings.
>> >> The wear on the rotor housings are well within acceptable limits
as long
>> as the apex seals remain intact. With the Mazda system of chrome over
>> steel.... cast iron apex seal wear is projected to be about 3,000
hours.
>> With Silicon Nitride ceramic apex seals wear is projected to be
30,000 hours.
>> Of course no one has worn out a ceramic apex seal yet.
>> -- >> Paul Lamar ...No rotor no motor.
> > > Paul,
> > Ethanol fuels will dissolve unprotected aluminum.
> > Doug
> > Looks like it is out for Porsche's, BMW's and Mercedes.
> Not to mention all the other companies that are planning to
> switch to un lined aluminum cylinder bores.
> > Paul Lamar ...No rotor no motor.


Paul

Anodized aluminum works.

Doug

I don't think so. That is a very thin coating.
I also don't think anodizing works on silcon. I could be wrong.

Paul Lamar ...No rotor no motor.

Paul, You are correct. The anodize would be very blotchy. I am at a loss
though
as to how the aluminum in the block would be effected (by ethanol) when
the bores are
prepared for final hone by hydrocloric acid.
Bill

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